Process for dyeing textile fibers with azo-disulfide and sulfur dyestuffs and dyed products thereof



1966 c. R. HOLTZCLAW ET AL, 3,264,053

PROCESS FOR DYEING TEXTILE FIBERS WITH AZO-DI$ULFIDE AND SULFUR DYESTUFFS AND DYED PRODUCTS THEREOF Filed March 11, 1963 W M R Q 51 a Z O a 00 I\ Q --2 a. 00

O 5Q 0 Q 00 1 Q 3 "Kai v 0'0 Q 00 Q -g Q9 INVENTORS.

CHARLES Haurzcuw JAMES H.8ENSON United States Patent 3,264,053 PROCESS FOR DYEING TEXTILE FIBERS WITH AZO-DISULFIDE AND SULFUR DYESTUFFS AND DYED PRODUCTS THEREOF Charles R. Holtzclaw, Mount Holly, and James H. Benson, Charlotte, N.C., assiguors to Martin-Marietta Corporation, a corporation of Maryland Filed Mar. 11, 1963, Ser. No. 264,413 9 Claims. (Cl. 8-27) The present invention relates to a method for dyeing textile fibers, and more particularly to an improved method for dyeing textile fibers with a dyestuff selected from the group consisting of azo-disulfide dyestuff and mixture of azo-disulfide dyestufi" and sulfur dye. The present invention also relates to textile fibers dyed with a combination of azo-disulfide dyestuff and sulfur dye.

The method of the present invention is particularly characterized in that it provides for the first time a commercially acceptable method for dyeing textile fibers with azo-disulfide dyestuif pigments. The method is further characterized in that higher color yield and improved levelness of appearance (uniformity of dyeing) are provided over that obtainable by prior methods for dyeing with azo-disulfide dyestuffs. Moreover, azo-disulfide dyestufifs which are reducible, poorly reducible and nonreducible in reducing agents at the normal temperature of reducing baths, e.g., about room temperature to about 160 B, may be used to dye textile fibers according to the method of the present invention.

The present method is further characterized in that it comprises the first known method for dyeing textile fibers with azo-disulfide dyestuffs which are non-reducible in reducing baths at normal temperatures.

Also, according to the method of the present invention, textile fibers may be dyed with a dye composition comprising a mixture of azo-disulfide dyestuif and sulfur dye. This is an important new dyeing method because it provides shades and hues that cannot be obtained by use of sulfur dye or azo-disulfide dyestulf alone, and provides increased brightness of shade over that attainable by use of sulfur dye alone. Sulfur dyes are among the least expensive dyes which have generally good fastness properties, but they do not have the extraordinary brightness of color that is characteristic of the azo-disulfide dyes. By dyeing the azo-disulfide dyestufi and the sulfur dye together, the inherent tinctorial value of the sulfur dye and the inherent brilliance of the azo-disulfide dyestulf are obtained.

Generally speaking, the method of the present invention is a method for dyeing textile fibers comprising the steps of padding onto the fibers an aqueous dye composition comprising azo-disulfide dyestuff pigment, reducing the dyestuff, oxidizing the dyestulf, scouring and drying the fibers. The reducing agent may be applied with the dyestuif or separately and prior to steaming the fibers.

Specifically, the method of the present invention may be carried out by one of the following processes comprising the following steps:

(1) Padding an aqueous pigment dispersion of dyestuff selected from the group consisting of azo-disulfide dyestuff pigment and azo-disulfide dyestuff pigment plus sulfur dye pigment onto the fibers, drying the fibers, applying reducing agent to the fibers, steaming the fibers, optionally washing the fibers, oxidizing the dyestuif, scouring and drying the fibers;

(2) Padding onto the fibers .a dye composition comprising reducing agent, water, and dyestuif selected from the group consisting of non-reduced azo-disulfide dyestuff pigment and non-reduced azo-disulfide dyestuff pigment plus reduced sulfur dye, steaming the fibers, option- 3,2fi4,053- Patented August 2, 1966 ally washing the fibers, oxidizing the dyestuif, scouring and drying the fibers;

-(3) Padding onto the fibers a dye composition comprising water, non-reduced azo-disulfide dyestuif pigment and reduced sulfur dye, drying the fibers, applying reducing agent to the fibers, steaming the fibers, optionally washing the fibers, oxidizing the dyestuff, scouring and drying the fibers;

(4) Padding onto the fibers a dye composition comprising water, alkali, delayed act-ion reducing agent, and dyestutf selected from the group consisting of non-reduced azo-disulfide dyestuff pigment and non-reduced azo-disulfide dyestuif pigment plus non-reduced sulfur dye, drying the fibers, steaming the fibers to reduce the dyestuflf, optionally washing the fibers, oxidizing the dyestuff, scouring and drying the fibers;

(5) Padding onto the fibers an aqueous dye composition comprising non-reduced azo-disulfide dyestuif pigment and dissolved non-reduced sulfur dye, drying the fibers, applying reducing agent to the fibers, steaming the fibers, optionally washing the fibers, oxidizing the dyestuff, scouring and drying the fibers;

(6) Padding onto the fibers water, delayed action reducing agent, alkali, non-reduced dissolved sulfur dye, and non-reduced azo-disulfide dyestuif pigment, drying the fibers, steaming the fibers to reduce the dyestuff, optionally washing the fibers, oxidizing the dyestuff, scouring and drying the fibers.

The term azo-disulfide dyestuff as used herein may be defined as the group of dyes having a reducible disulfide group (SS) connected between aromatic nuclei to which are attached color bodies containing azo groups (N=N), and also the group of dyestuffs which, upon reduction and oxidation, produce a disulfide group connected between aromatic nuclei to which are attached color bodies containing azo groups. The azo groups may either be connected to the same aromati nuclei to which the disulfide group is connected, or they may be found elsewhere in the color bodies. Illustrative examples of the above three types of azo-disulfide dyestuffs are the dyestuff formed by coupling one mole of diazotized S-thiocyano-Z-amino-toluene to one mole of beta-naphtha], which dyestuff upon reduction and subsequent oxidation produces 3:3 dimethyldiphenyldisulfide 4:4 bis (azo beta naphthol); the dyestuff formed by coupling one mole of diazotized para-nitroaniline to one mole of 1 phenyl 3 methyl 5 pyrazolone, reducing and diazotizing the resulting product and coupling it to one-half mole of beta-hydroxynaphthoic acid dithioanilide; and the dyestuff formed by coupling one mole of tetrazotized 4:4 diaminodiphenyldisulfide to two moles of 1-phenyl-3-methyl-5-pyrazoline.

Certain azo-disulfide dyestuffs have been known for more than fifty years, but the azo-disulfide dyestuffs prepared by coupling a mole of tetrazotized diaminodiphenyldisulfide with two moles of an azo coupling component have never gone into commercial production or use, primarily because there has remained unknown a useful commercial method for applying the dyestuffs to textile fibers in which the resulting dyeings have commercially acceptable color yield. As understood in the dyeing art, the term color yield refers to the depth of shade obtained from a given amount of dyestuff.

The following methods have been suggested for dyeing textile fibers with azo-disulfide dyestuffs, but each of the suggested methods has disadvantages and limitations.

It has been suggested to exhaust a reduced solution of azo-disulfide dyestuff onto textile fibers from a sodium sulfide bath. The well-known raw stock, beck and jig dyeing methods are characteristic of the exhaustion technique. The difiiculties with the exhaustion method in the dyeing of azo-disulfide dyestuffs are that those azodisulfide dyestuffs which are non-reducible at the normal temperatures of dye baths cannot be applied by the exhaustion method; those azo-disulfide dyestuffs which are poorly reducible at the normal temperatures of dye baths cannot be applied satisfactorily by the exhaustion method; and only those azo-disulfide dyestuffs which are reducible or converted into their soluble state at the normal temperatures of dye baths may be applied to textile fibers, and even in connection with these azo-disulfide dyestuffs the exhaustion method is not commercially acceptable because the exhaustion technique depends on long or repeated immersion of textile fibers into the reduced dyebath and upon the physical afiinity of the dyestutf for the fibers, and inasmuch as azo-disulfide dyestuffs have poor affinity for textile fibers too much dyestuff remains in the dyebath and there is poor color yield. In summary, the exhaustion method is commercially unsuitable for dyeing azo-d-isulfide dyestuffs because it is limited to dyeing those azo-disulfide dyes which are soluble at the normal temperatures of reducing baths, it requires too much time, it provides poor color yield, and the dye is not fixed firmly on the fibers.

Others have attempted to conduct exhaustion dyeings at low temperature, on the theory that high temperatures decomposed the azo group in the dye molecule. This further limited the types of azo-disulfide dyestuffs which could be applied by the method, and did not improve the color yield of the resulting dyeing. Surprisingly, the present method is advantageously conducted with steam, without apparent destruction of the azo-disulfide dyestuff.

Others attempted to add caustic and an electrolyte, such as sodium sulphate, to a sodium sulphide reduced azo-'disulfide dyestutf solution. However, the electrolyte did not salt out but a small portion of the dyestuff onto the fiber, and the color yield remained poor.

Others added sol-ubilizing substituents, such as sulphonic acid, to the azo-disulfide molecule to render the dyestuff more soluble. This rendered the dyestuffs so soluble that they were not wash fast.

Others synthesized azo-disulfide dyestuffs by coupling a diazotized ortho-aminophen-ol to an azo component containing a disulfide group. It was suggested that these dyestuffs be applied to fibers by exhaustion from a sulphide bath, and that the dyeings be after-treated with a metal salt to improve the fastness. The basic difficulties with this method are that it is time consuming and there is poor col-or yield.

US. Patent No. 3,088,790 discloses useful methods for dyeing azo dyes having pendant thiosulfate groups attached via bridging members to aryl groups of the dyestulf. However, those azo-disulfide dyes prepared by coupling a mole of tetrazotized diaminodiphenyldisulfide with two moles of azo coupling component may not be dyed satisfactorily by this method.

According to the method of the present invention, the above disadvantages and limitations of the prior art have been overcome and additional advantages have been provided as follows.

According to the present invention, a high speed, continuous, economical method for dyeing textile fibers with azo-disulfide dyestuffs has been developed. The primary advantages of the method are that high color yield and improved levelness of appearance are obtained. Also, a method has been provided for the first time whereby all of the azo-disulfide dyestuffs may be applied to textile fibers, e.g., those which are reducible, poorly reducible, and non-reducible in reducing baths at normal temperatures. The provisions for the first time of a method whereby the azo-disulfide dyes which are non-reducible at normal temperatures may be applied to textile fibers is in itself a valuable contribution to the dyeing art because a number of the members of this group of dyes have extraordinary brightness and no change in shade or light fastness on subsequent resin treatment. Thus, according to the present invention, it has been made possible for the first time to make dyeings with a valuable class of dyestulf pigments in a commercial manner.

According to the method of the present invention, one of the following dye compositions may be applied to the textile fibers: (a) an aqueous pigment dispersion of non-reduced azo-disulfide dyestuff, (b) an aqueous pigment dispersion of non-reduced azo-disulfide dyestulf plus non-reduced sulfur dye pigment, (c) an aqueous pigment dispersion of non-reduced azo-disulfide dyestuif plus reducing agent, in which case the reducing agent may be one of the conventional salts or a delayed action type, (d) an aqueous pigment dispersion of non-reduced azodisulfide dyestuff pigment, reducing agent, and reduced sulfur =dye, (e) an aqueous pigment dispersion of nonreduced azo-disulfide dyestuff, soluble non-reduced s-ulfur dye, and optionally a delayed action reducing agent. When reducing agent is incorporated in the dye composition azo-disulfide dyestuffs which are not reduced in the dye composition should be utilized; in the case of the delayed action reducing agents, this is not applicable because they do not reduce the dye in the dye composition, and until reaching the steamer. In each of the above instances, the azo-disulfide dyestuff pigment is reduced in the steamer.

The amount of dyestuff utilized in the dye composition will vary with the depth of shade desired, higher concentrations being required to obtain deeper shades than to obtain lighter shades. Generally speaking, about 2 oz. by weight of concentrated dyestuff per gallon of dye composition is suitable to provide a medium shade, and from about 0.2 oz. to 8 oz. of concentrated dyestuff per gallon of dye composition will provide a wide range of depth or shade.

The dye composition may be advantageously applied to the fibers by passing them through a pad box containing the dye composition. The temperature of the dye composition may be maintained from about room temperature to about 170 F., and prefer-ably within the range of about l50 F.

In the case of dye compositions which do not contain reducing agents, the steps subsequent to padding comprise drying, applying reducing agent, steaming, optional washing, oxidizing, scouring and drying.

In the case of dye compositions which contain reducing agents, the steps subsequent to padding comprise steaming, optional washing, oxidizing, scouring and drying. Also, these may be dried subsequent to padding on the dye composition, provided either that a delayed action reducing agent is used as the reducing agent, or that additional reducing agent is applied subsequent to drying and prior to steaming.

In some instances, the drying prior to steaming improves the levelness of appearance of the resulting dyemg.

The reducing agent may be any of the conventional reducing agents, such as sodium sulphide, sodium polysulphide, sodium sulfhydrate, mixtures thereof, etc., although sodium sulphide is preferred for reasons of economy; or, alkali and one of the delayed action reducing agents, such as thiorurea, sodium s-sodiocarboxy methyl thiosulfate,

s HOOCRiS( 'iSRzOOOH wherein R and R are alkylene groups, or a salt of said H0oo-R1siisR2c00H in which case reduction of the azo-disulfide dyestuff and sulfur dye will occur in the steamer.

The amount of reducing agent needed will be determined by the particular dyestuif being applied, the amount of dyestuif, and the capacity of the reducing agent selected for hydrogen donation. Since the use of reducing agents is well understood in the dyeing art, it will suffice to say that enough reducing agent is utilized to effect reduction of the dyestulf. When 2 oz. of concentrated dyestuif per gallon of dye composition is utilized, about 6 oz. of sodium sulphide will effect the reduction. Generally speaking, about 2-10 oz. of reducing agent per gallon of water will be satisfactory.

When the reducing agent is applied to the fibers from a separate bath, it may be maintained at from about room temperature to 190 F., and preferably at about 130160 F.

The steaming completes the reduction of the dyestulf by the reducing agent. Steaming the fibers for about one-half to five minutes at about 212 F.-225 F. is satisfactory to complete the reduction; about one-half to one minute is suggested when the conventional inorganic reducing agents are used and about two minutes When the delayed action reducing agents are used. Also, it is suggested that the steaming be done with neutral air-free steam.

Following steaming, the fibers are preferably washed with water and then passed through an acid-oxidizing bath, although the washing step may be omitted and the oxidizing bath may be neutral or alkaline. The washing step is suggested to remove excess reducing solution and other extraneous materials, and to prevent dilution of the subsequent oxidizing bath. Also, when the fibers pass directly from the steamer to an acid solution, the excess reducing agent reacts with the acid and hydrogen sulfide gas is generated; production of hydrogen sulfide gas may be avoided by either using a neutral or alkaline oxidizing bath or by washing the fibers prior to passing them into the acid; however, if the fibers are to pass from the steamer into an :acidic solution, it is suggested that the acidic bath be covered with a hood and that the hydrogen sulfide gas be carried away by means of a connecting duct and exhaust fan. There may be considerable variation in the steps following steaming, for example, the fibers may be steamed and then (a) washed and passed through an oxidizing agent, or (b) passed through acid, Washed, and passed through an oxidizing agent, or (c) passed through an oxidizing bath.

Although neutral or alkaline oxidizing baths may be used, it is preferred to use an acid-oxidizing bath, as the acid assists in increasing the color yield and as the acidoxidizing bath provides substantially more color yield than acidifying, washing and oxidizing in separate steps.

The amount of oxidizing agent required will depend on the particular dyestuif selected, the amount of dyestuif selected, the amount and type of'reducing agent previously employed, whether the fibers have been washed prior to oxidizing, and on the capacity of the particular oxidizing agent for'oxygen donation. Inasmuch as the use of oxidizing agents is well understood in the dyeing art, it will suifice to state that enough oxidizing agent is utilized to oxidize the dyestuff. When 2 oz. of concentrated dyestulf per gallon is reduced by oz. of sodium sulphide per gallon and the fibers are subsequently washed, 1 oz. of glacial acetic acid and 1 oz. of sodium bichromate per gallon will make the corresponding oxidation. Generally speaking, about 0.5-2 oz. of oxidizing agent per gallon of water and enough acid to bring the pH to 4-6 is suitable.

Following oxidation, the fibers are scoured and dried. The drying may be efiected in any continuous manner, such as housed tenter frame, heated cans, or loop dryer.

It will be noted that the above process may be conducted in a continuous manner throughout, with such things as pad boxes, steamers and dryers in tandem, and may be conducted at high speeds, for example 30-100 yards per minute.

The chemistry of the dyeing reaction is believed to be as follows. When the azo-disulfide dye contains a di- 6 sulfide linkage, R SSR which is considered to be the oxidized state, the dyestufi is reduced to form its normal reduced state. The oxidizing agent restores the dyestufi to its oxidized state, firmly fixed upon the fibers. When the azo-disulfide dyestufr' is one which, upon reduction and subsequent oxidation produces a disulfide group connected by aromatic nuclei, the reducing agent converts R QSX and R fiSX, wherein X may be such as a cyano or sulfonic group, to R -S-Na and R SNa, and the oxidizing agent oxidizes them into R fiSSR firmly fixed upon the fiber.

Textile fibers that may be dyed according to the invention include cotton, nylon and regenerated cellulose.

One form of apparatus that may be conveniently employed in carrying out the method of the invention is illustrated in the accompanying drawings, forming a part of this application, in which:

FIG. la is a diagrammatic view, broken away, showing a portion of the apparatus; and

FIG. 1b is a diagrammatic view, broken away, showing a continuation of the apparatus of FIG. 1a.

The following illustrative examples are given.

Example 1 Referring now to FIGS. 1a and lb for a better understanding of the present invention, conventional prebleached, dry, woven, cotton fabric 10 weighing 4 oz. per sq. yd. is passed at a rate of 50 yards per minute over guide roll 11 and into pad box 12 having therein at 150 F. an aqueous pigment dispersion of azo-disulfide dye, which dispersion, contains 2 oz. by weight per gallon of water of the concentrated azo-disulfide dyestuif formed by coupling one mole of tetrazotized 2,2'-dichloro-4:4- diaminodiphenyldisulfide to two moles of naphthol AS- OL (azoic coupling component #20, Cl. Part II, No. 37,530), The fabric is passed between rubber coated pressure rollers 13 adjusted to permit the fabric to retain of dye dispersion, based on the fabric weight. The fabric is then passed into loop drier 14 maintained at 240 F. where it remains for about one minute and is substantially dried. The fabric passes over guide roller 15 and into pad box 16 having therein at F. a reducing agent containing 10 oz. by weight of sodium sulphide per gallon of water. The fabric passes between rubber coated pressure rollers 17 and into steamer 18 maintained at 212-215 F., where the fabric is subjected to neutral air-free steam for one minute. The fabric passes over guide roller 19 and into pad box 20 containing water at 140 F., between rubber coated pressure rollers 21, into pad box 22 having therein at 140 F. an acid-oxidizing agent containing 1 oz. of glacial acetic acid and 1 oz. of sodium bichromate per gallon of water, between rubber coated pressure rollers 23, into pad box 24 having therein water at F., between rubber coated pressure rollers 25, into pad box 26, containing at 170 F. 0.5 oz. by weight of soap per gallon of water, between rubber coated pressure rollers 27, into pad box 28 containing water at 170 F., between rubber coated pressure rollers 29, into pad box 30 containing water at 170 F., between pressure rollers 31, and is then serpentined about 16 rotating, steam-heated, cylindrical, stainless steel, drying cans 32-47 maintained at an internal steam pressure of 15 p.s.i. to dry the fabric. The dyedvfabric is thereafter collected.

Example 11 This example is the same as Example I above, except that pad box 12 contains 1 oz. per gallon of water of the azo-disulfide dyestuff utilized in Example I plus 1 oz. per gallon of Sulfur Red 5 (0.1. Part II, No. 53,830), as a dispersed pigment, instead of the dye composition utilized in Example I.

7 Example III This example is the same as Example I above, except that the dye composition used in pad box 12 is an aqueous pigment dispersion of azo-disulfide dyestutf consisting of 2 oz. by weight per gallon of water of the concentrated azo-disulfide dyestuff formed by coupling one mole of tetrazotised 424'-diaminodiphenyldisulfide to two moles of 1-phenyl-3-methyl-5-pyrazolone, instead of the dye composition used in Example I; and except that pad box 20 is by-passed; and except that pad box 22 is covered with a hood having a duct and exhaust fan (not shown) for exhausting the hydrogen sulphide gas.

Example I V This example is the same as Example III above, except that pad box 12 contains, per gallon of water, 1.6 oz. of the concentrated azo-disulfide dyestuff utilized in Example III plus 0.4 oz. of concentrated Sulfur Yellow 2 (C.I. Part II, No. 53,120) as a dispersed pigment, instead of the dye composition utilized in Example III.

Example V To viscose rayon fabric weighing 3 oz. per square yard is padded on, at room temperature, a dye composition consisting of, per gallon of Water, 5 oz. of sodium sulfide reducing agent and 2 oz. of the concentrated azo-disulfide dyestuif formed by coupling one mole of diazotized meta-nitroaniline to one mole of 3-methyl-5-pyrazolone, reducing the resulting product with sodium sulphydrate, filtering, drying, and condensing one mole of the dried product with one mole of 2,4,6-trichloro-1,3,5-triazine in the presence of acetone and soda ash at 5 C., and reacting one mole of'the resulting product with one-half mole of 4:4'-diaminodiphenyldisulfide at 20 C. as a pigment dispersion. The fabric is then passed through squeeze rolls to permit about 85% pick-up of dye composition based on fabric weight, steamed for 5 minutes in neutral air-free steam at 212-215 F. to reduce the dyestuff, passed through a hooded and vented pad box containing 1 oz. of glacial acetic acid and 1 oz. of sodium bichromate per gallon of water at 140 to oxidize the dyestufi, and then scoured and dried as above.

Example VI This example is the same as Example V above, except that the fabric is passed through a pad box containing water at 150 F. and then through squeeze rolls, subsequent to the steaming step and prior to the oxidizing step in Example V, and except that no hood is required for the pad box.

Example VII This example is the same as Example V above, except that nylon fabric is used; except that the dye composition which is at room temperature contains per gallon of water, 7 oz. of Sodyesul Liquid Green NCF (which is 1.4 oz. concentrated Sulfur Green 2, Cl. Part II, No. 53,571, reduced with an excess of sodium hydrosulfide), 5 oz. of sodium sulfide, and 1 oz. of the concentrated non-reduced azo-disulfide dyestufi formed by diazotizing one mole of para-nitroaniline and coupling it to one mole of acetoacet-ortho-anisidide at C., filtering, wash ing, and reducing the resulting product with sodium sulphydrate, condensing one mole of the resulting product with one mole of 2,4,6-trichloro-1,3,5-triazine in the presence of acetone and soda ash at C., and reacting one mole of the resulting product with one-half mole of 2,2'-dichloro-4:4-diaminodiphenyldisulfide at 20 C. as a dispersed pigment.

Example VIII This example is the same as Example VII above, except that cotton fabric weighing 4 oz. per square yard is substituted for the nylon fabric, and except that the fabric is passed through a pad box containing water at 150 C, and then squeezed by nip rolls, subsequent to the steaming step and prior to the oxidizing step of Example VII. Also, the pad box need not have a hood.

Example IX This example is the same as Example I above, except that the dye composition used in pad .box 12 is an aqueous pigment disperseion of azo-disulfide dyestutf consisting of 2 oz. by weight per gall-on of water of the concentrated azo-disulfide dyest-ulf formed by coupling one mole of diazotized meta-nitraniline to 3-methyl-5-pyrazolone, reducing the resulting product with sodium sulphydrate, filtering, drying and condensing one mole of the dried product with one mole 2,4,6-trichloro-1,3,5-triazine in the presence of acetone and soda ash at 5 C. and reacting one mole of the resulting product with one-half mole of 4:4-diaminodiphenyldisulfide at 20 C. The resulting product is heated to C. with one mole aniline which condenses with the remaining chlorine in the ring.

Example X This example is the same as Example IX above except that pad box 12 contains 1 oz. per gallon of water of the azo-disulfide dyestuif utilized in Example IX, plus 5 ozs. per gallon of water of Sodyesul Liquid Blue 4GBCF, which is 1 oz. of concentrated Sulfur Blue 8 reduced with an excess of sodium sulfide and sodium hydrosulfide.

Example XI An aqueous pigment dispersion of azo-disulfide dyestuif (2 oz. per gallon of water of the azo-disulfide dyestufi formed by coupling one mole of diazotized S-thiocyano-2-aminotoluene to one mole of beta-naphthol) is padded on cotton fabric at room temperature, pickup. The fabric is dried to substantial dryness, passed through a pad box containing 5 oz. of sodium polysulfide per gallon of water at 150 F., steamed for one minute with neutral air-free steam at 2'12215 F., passed through a hooded and vented pad box containing 1 oz. of glacial acetic acid per gallon of Water at F passed through a pad box containing water at F., passed through nip rolls, passed in an acid-oxidizing bath containing 1 oz. glacial acetic acid and 1 oz. sodium bichromate per gallon of water at 140 F., scoured and dried.

Example XII onto cotton fabric, the fabric is dried to substantial dryness at 240 F., steamed with neutral air-free steam for 2 minutes at 212215-F.; and then washed, oxidized, scoured and dried as described in 19-47 of Example 1.

Example XIII This example is the same as Example I above, except that a dye composition consisting of, per gallon of water, 3 oz. concentrated Sulfur Black No. 1, CI. Part II, No. 53185, in solubilized, oxidized, non-substantive form, which is the water soluble thiosulfonic acid derivative of the sulfur dye, and 1.2 oz. of the concentarted azodisulfide dyestulf formed :by coupling one mole of diazotized meta-nitroaniline to one mole of 3-methyl-5- pyrazolone, reducing the coupled product with sodium sulphydrate, filtering, drying, condensing the resulting dried product with one mole of 2,4,6-trichloro-1,3,5-triazine in the presence of acetone and soda ash at 5 C., and reacting one mole of the resulting product with onehalf mole of 4:4'-diaminodiphenyldisulfide at 20 C. as a dispersed pigment, is substituted for the dye used in pad box 12 of Example I.

Example XIV This example is the same as Example X above, ex cept that the washing subsequent to steaming is eliminated by by-passin-g pad box 20, and box 22 is hooded as discussed above.

Example XV This example is the same as Example XII above, except that the washing subsequent to steaming is eliminated by by-passing pad box 20, and box 22 is hooded as discussed above. Example XVI This example is the same as Example XII above, exept that 0.2 -oz. of Sulfur red 5, as dispersed pigment, is added to each gallon of the dye composition of Example XII.

Example XVII This example is the same as Example XIII above, except that oz. of thiourea and 3 oz. of NaOH are added to each gallon of the dye composition of Example XIII, and except that the reducing agent of pad 16 is bypassed.

Example XVIII This example is the same as Example XVII, except that the washing following steaming is omitted by bypassing box 20. In connection with the use of the delayed action reducing agents, it should be noted that they do not react with acid to produce hydrogen sulfide gas.

We claim:

1. A method for dyeing textile fibers comp-rising the steps of padding onto the fibers an aqueous dye composition comprising azo-disulfide dyestuff pigment, reducing the dyest-uif whereby the azo-disulfide dyestuff pigment is reduced at the disulfide bond, oxidizing the dyestuff, scouring and drying the fibers.

2. A method for dyeing textile fibers comprising the steps of padding onto the fibers an aqueous dye composition comprising dyestuif selected from the group consisting of azo-disulfide dyestuff pigment and azo-disulfide dyestuff pigment plus sulfur dye pigment, drying the fibers, applying reducing agent to the fibers, steaming the fibers, oxidizing the dyestufi, scouring and drying the fibers.

3. A method as defined in claim 2, and further characterized in that the fibers are Washed subsequent to steaming and prior to oxidizing the dyestutf.

4. A method for dyeing textile fibers comprising the steps of padding onto the fibers a dye composition comprising water, alkali, delayed action reducing agent, and dyestuif selected from the group consisting of non-reduced azo-disulfide dyestuff pigment and non-reduced azo-disulfide dyestulf pigment plus non-reduced sulfur dye, steaming the fibers to reduce the dyestuff whereby the azodisulfide dyestuff pigment is reduced at the disulfide bond, oxidizing the dyestuff, scouring and drying the fibers.

5. A method for dyeing textile fibers comp-rising the steps of padding onto the fibers a dye composition comprising water, delayed action reducing agent, alkali, dissolved non-reduced sulfur dye, and non-reduced azodi'sulfide dyest'uff pigment, drying the fibers, steaming the fibers to reduce the dyestuif whereby the azo-disulfide dyestuif pigment is reduced at the disulfide bond, oxidizing the dyestuff, scouring and drying the fibers.

6. Textile fibers dyed with a mixture of azo-disu'lfide dyestuff and sulfur dye.

7. Textile fabric dyed with a mixture of azo-disulfide dyestuff and sulfur dye.

8. Cellulosic textile fibers dyed with a mixture of azodisulfide dyestulf and sulfur dye.

9. Cellulosic textile fabric dyed with a mixture of azo-disulfide dyestuff and sulfur dye.

References Cited by the Examiner UNITED STATES PATENTS 2,002,406 5/ 1935 Lantz 8-27 X 2,174,486 9/ 1939 Chambers 8--37 2,663,613 12/1953 Gibson 8--37 3,088,790 5/1963 Schultheis 81.213 3,098,064 7/ 1963 Schultheis 81.213

FOREIGN PATENTS 590,397 2/1961 Belgium. 899,944 6/ 1945 France.

OTHER REFERENCES Chem. Abstracts, vol. 49, p. 15181 (1955). Derwent Belgian Report No. 71A, pp. C1 and C2.

NORMAN G. TORCHIN, Primary Examiner.

D. LEVY, Examiner.

J. HERBERT, Assistant Examiner. 

1. A METHOD FOR DYEING TEXTILE FIBERS COMPRISING THE STEPS OF PADDING ONTO THE FIBERS AN AQUEOUS DYE COMPOSITION COMPRISING AZO-DISULFIDE DYESTUFF PIGMENT, REDUCING THE DYESTUFF WHEREBY THE AZO-DISULFIDE DYESTUFF PIG- 